The Windows 8 Pro version of Microsoft’s Surface tablet may be getting all the attention lately, but we’re still waiting to see if Microsoft has what it takes to make the lower-end Surface RT catch on in any kind of serious way. We just took a look at some figures that suggested Microsoft had shipped around 900,000 of these tablets, but there’s some degree of uncertainty over those numbers, and while Microsoft may have actually shipped closer to 1.25 million Surface RT tablets, end-user sales could be significantly lower, to the tune of around 700,000, suggesting there are still a lot of units taking up warehouse space. What may be most troubling for Microsoft, though, are reports that return rates for the Surface RT have been “very high.”

This analysis comes from IHS iSuppli, and while it doesn’t put a specific figure to those returns, it believes they’re well above industry norms. What’s interesting is that the problem reportedly isn’t due to any defect in the hardware itself, but users becoming frustrated with Windows RT itself.

On one hand, that could be good news for the Surface Pro, as even though it still runs Windows 8, the greater app compatibility and flexibility offered by Win 8 Pro could be enough to win over users who were previously dissatisfied with the Surface RT. On the other hand, this could simply speak to broader issues with acceptance of Windows 8 in general, which would spell bad news for any flavor Surface.